Today, I have added an on/off button to the battery pack Ed made for me. I have used a car/lorry 12V on/off button from Halfords, 25A cabling and connectors. This button goes between the 75AH leisure battery and inverter and is meant to avoid the situation where I accidently leave the inverter turned on draining the battery as happened to me recently. It took quite some time to get this working although for some reason I have not managed to get the 12V light to come on on the switch when it is turned on. More accurately, I did get that working too when the switch was not installed on the side of the case but it has not worked since I drilled the hole and screwed it on to the case!
The location of the switch below the plug sockets is to avoid the switch foulibg the handle of the case.
Ed Mann built a fantastic battery pack for several members of RAG including myself. These packs are based around a 75AH leisure battery and provide 12V and 230V outputs abd plenty of juice to power anything we need in the field from mounts to laptops.
However they are quite heavy. To help with transpirt i purchased a Homebase foldable sack truck.
There was still a problem left – the battery pack is housed in a plastic box that tends to slip on the sack truck and fall off. Bungy cords provided part of the solution and today I added the second aspect: I glued 3mm rubber sheet to the bottom of the battery pack and now it will never slip again! To acheive this, I had to empty the battery box first before I coukd turn the box over, but I got there eventually and aI am pleased with the result.
Today, I housed the new calibration light – I put four of the RELCO starter neon bulbs in the lid of a box – I attached them to a connection block inside the box.
In this way, I have four neon bulbs ready to use. I only connected one at a time. Each bulb has life span of 90 hiurs do when one burns out, moving the wires indide the box to the next bulb along allows the calibration light to continue to ne used.
As mentioned in the previous post, I have added a boc from ebay which will turn off the light after twenty minutes preserving the life of the bulbs when I inevitably forget to turn them off on the field!
The whole set up runs on 240V via an inverter on a leisure battery. I have ordered a RCD for safety and used boxes designed for external use and sealed all holes with a glue gun to minimize moisture ingress.
My first calibration spectrum taken using the above can be seen at this post, which follows on from the above:
Please note this project uses potentially dangerous/life threatening 240V mains electricity supply – please ensure you are qualified to work with this or ask someone with such qualifications to do this work for you.
The following is a description of what I did rather than a recommendation for how this should be done.
My modifications required began with my removing the neon bulb from its RELCO flourescent light starter casing and attaching 2 x 47 Kiloohm resistors in parallel to one limb of the neon bulb. The bulb is then simply connecting to 240V supply. Once I confirmed this worked, I connected a delay switch unit – this automatically switches the light off after 20 mins to preserve the life of the bulb as the neon bulbs in these starters have a life expectancy of only 90 hours each.
The delay switch unit is the box with printed circuit in the last photo – I did not make this but bought it off eBay.
I now need to mount the bulb in a housing so it can be safely used outside for calibrating my spectrometers at the telescope.
The photos below refer to the above process.
There is a follow up post available to the above which describes the completion of this project:
A couple of months ago I brought my ‘work in progress’ scope along to an introducing astronomy night.
I’ve had to teach myself anodising to finish it, I’m quite pleased with it, although I’m going to have to do some more tuning of the speed reducer – the ball bearings are causing the grooved stainless steel rod to distort making it go loose. I have a plan but it means making or finding a specially shaped grindstone.
Ed’s laser pointers with integratedvheater straps and powered from 12V car battery thay he madr for Damian and myself are fantastic. However the power transistor gets quite hot so he came around yesterday and swapped the transistor for a small board that switches power on and off at high frequency so that less power is used and it does not get hot. Works brilliantly! Thanks Ed. This is what we should be able to buy commercially but can’t….
Lee and Nick talked about 6 objects to observe in night sky and various telescope finder devices including Lee’s homemade version of a device similar to a Telrad – a beefy version with 50mm binocular lens in it, 1/10 wave mirror and in-built heater! He is suggesting a workshop to make our own versions of the same but improved over the commercial original- sign me up!
After Lee and NIck’s talk, I gave a brief demonstration of the DIY Spectroscope – thankfully it worked producing instant spectra for the lights in the room!
Nick Cox (left) and Lee Bale (right) give their talk at RAG:
Rhys tries out Lee’s homemade version of Telrad finder: